This page provides tables of sample size required to establich a Cronbach's Alpha. The tables are in 3
levels of power (0.8, 0.9, and 0.95) and 4 levels of probabilities of Type I Error (α) (0.1, 0.05, 0.01, and 0.001),
for reliabilities from 3 to 15 variables, at Cronbach Alpha values at 0.02 intervals.

Sample size for both one tail and two tail models are provided, but most researchers use the one tail model as they
are interested only in testing against the null hypothesis.